Alligator

An alligator, sometimes called a gator, is a large reptile belonging to the genus Alligator in the family Alligatoridae of the order Crocodilia. There are two main kinds of alligators today: the American alligator (A. mississippiensis) and the Chinese alligator (A. sinensis). Scientists have also found fossils of several kinds of alligators that no longer exist. Alligators first appeared about 37 million years ago during a time called the late Eocene epoch.

The word "alligator" probably comes from a changed version of el lagarto, a Spanish phrase meaning "the lizard". This is what early Spanish explorers in Florida called these animals. Over time, English speakers used different spellings such as allagarta and alagarto before settling on "alligator".

Alligators are special because they can live in places that are cooler than where most other crocodile relatives live. While they usually like warm areas close to the equator, they can also survive colder winters in some parts of their home range.

Evolution

Alligators and caimans separated in North America during the early Tertiary or late Cretaceous, around 53 to 65 million years ago. The Chinese alligator separated from the American alligator about 33 million years ago, likely traveling across the Bering land bridge during the Neogene period. The modern American alligator appears often in fossils from the Pleistocene. Scientists mapped the alligator's mitochondrial genome in the 1990s, and the full genome was published in 2014, showing that alligators evolve more slowly than mammals and birds.

Phylogeny

The genus Alligator is part of the subfamily Alligatorinae. This subfamily is closely related to another group called Caimaninae, which includes the caimans. Together, these two groups make up the family Alligatoridae. The diagram below shows how alligators are related to other creatures in their family.

Species

Extant

Extinct

• Alligator hailensis
• Alligator luicus
• Alligator mcgrewi
• Alligator mefferdi
• Alligator munensis
• Alligator olseni
• Alligator prenasalis
• Alligator thomsoni

Description

An average adult American alligator weighs about 360 kg (790 lb) and is 4 meters (13 feet) long, but they can sometimes grow up to 4.4 meters (14 feet) long and weigh over 450 kg (990 lb). The largest ever found in Louisiana measured 5.84 meters (19.2 feet). The Chinese alligator is much smaller, usually not longer than 2.1 meters (7 feet) and weighing less than 45 kg (100 lb).

Adult alligators are black or dark olive-brown with white undersides. Young alligators have bright yellow or whitish stripes that help them hide among reeds and wetland grasses. Alligators can live up to 50 years, and some have been known to live over 70 years. One famous alligator named Saturn lived to be 83 or 84 years old. He was born in 1936 in Mississippi and spent most of his life at the Moscow Zoo. Another old alligator named Muja lived in his 80s and was at the Belgrade Zoo in Serbia.

Habitat

Alligators live in fresh water places like ponds, marshes, wetlands, rivers, lakes, and swamps. They are mainly found in the southeastern United States, including all of Florida and Louisiana, and parts of Georgia, Alabama, Mississippi, South Carolina, North Carolina, East Texas, Oklahoma, and Arkansas. Louisiana has the most alligators. These animals help keep ecosystems healthy by creating holes that give other creatures a place to live during dry times.

The Chinese alligator is only found in the Yangtze River valley and is in big danger of disappearing, with very few left in the wild. There are more Chinese alligators in zoos than in nature. Places like Rockefeller Wildlife Refuge in Louisiana and Miami MetroZoo work to protect this species.

Behavior

Alligators make many different sounds, like bellows and hisses. You can hear some of these sounds in the audio clips above.

Large male alligators usually stay alone and guard their own area. Smaller alligators are often found together in groups. Alligators can move in two ways on land: they can crawl with their belly on the ground, or they can walk upright on all four legs.

Even though alligators are heavy and move slowly, they can run quickly for short distances. They usually eat small animals they can catch in one bite. For bigger food, they might drag it into the water or use a spinning motion called a "death roll" to tear off pieces they can eat.

Alligators are usually scared of people and will try to leave if they see someone coming. But if people get too close or feed them, the alligators might start to see humans as a source of food, which can be dangerous. Feeding wild alligators is not allowed in Florida.

Diet

Alligators eat different foods depending on their age and size. When they are young, they eat small animals like fish, insects, snails, crustaceans, and worms. As they grow bigger, they start eating larger animals such as bigger fish, turtles, nutrias, muskrats, birds, deer, and other reptiles. Sometimes they will also eat animals that have already died, called carrion.

Larger alligators can sometimes surprise animals like dogs, Florida panthers, and black bears. Even though alligators are strong animals, they usually don’t see people as food. However, if a person gets too close or bothers them, an alligator might defend itself and attack.

Reproduction

Alligators grow to about 1.8 meters, or 6 feet, long when they become adults. Their mating season is in late spring. During April and May, they gather in groups and make loud noises together, often soon after sunrise. Males also show off by slapping their heads.

In summer, female alligators build nests from plants. As the plants break down, they give off heat that helps the eggs hatch. The temperature inside the nest decides if the baby alligators will be male or female. Cooler nests produce more females, while warmer nests produce more males. When the eggs are ready, the baby alligators use a special tooth to break out of their shells. The mother protects the nest and helps the babies reach the water. She continues to watch over them for about a year if they stay nearby.

Anatomy

Alligators have a special way of breathing that is different from most animals. Instead of air moving in and out the same way, like in humans, air moves in one direction through their lungs. This helps them get oxygen better.

Alligators also have a two-part stomach that helps them digest their food. One part has small stones that grind up the food, making it easier to digest. The other part is very acidic, which helps break down the food even more. After eating, an alligator's metabolism can increase up to four times, helping it get energy from its meal. They also have special folds in their intestines that help absorb nutrients better.

During times when alligators aren't eating, called brumation, they can use their own fat to get energy until they find food again. Alligators have bony, armored skin that helps protect them and also helps with calcium balance. They also have strong, flat tails that help them swim quickly.

There are very rare white alligators called albino and leucistic, which can only survive in captivity. The Aquarium of the Americas in New Orleans has a few of these special alligators.

Human uses

Alligators are raised on farms for their meat and skin. Their skin is treated and used to make items like bags, shoes, and belts. Alligators also help people by controlling animals like nutrias and muskrats. Many people enjoy visiting swamps to see alligators on special tours. Alligator meat is also eaten by people.

Differences from crocodiles

Alligators and crocodiles look similar but have some key differences. One easy way to tell them apart is by their teeth. When an alligator closes its mouth, you can only see the top teeth. With a crocodile, both the top and bottom teeth are visible, giving it a "toothy grin."

Alligators also have wider, U-shaped snouts, while crocodiles have more pointed, V-shaped snouts. Crocodiles can live in salty water because they have special glands that remove extra salt. Most alligators do not have this ability and prefer freshwater habitats, though some larger alligators can be found in certain coastal areas.

Both animals have special sense organs in their jaws that help them feel movements in the water. However, crocodiles have these organs all over their bodies, which may help them sense things in their environment better.

Image gallery of extant species

Here are some pictures of alligators in different places. You can see an alligator in the Everglades National Park, at the Canberra Zoo in Australia, and in the Louisiana bayou. There is also a picture of a young alligator found in the Everglades National Park.